Rooting of Poa annua L., Poa pratensis L., and Agrostis palustris Huds. at Three Soil Bulk Densities1

Abstract Poa annua L. is usually considered an inherently shallow‐rooted grass. A growth‐chamber study was designed to compare the rooting of P. annua, P. pratensis L., and A. palustris Huds. at bulk densities of 1.1, 1.25, and 1.4. Treatments included P. annua and P. pratensis cut at 3.8 cm, and P. annua and A. palustris cut at 1.3 cm. Root samples were taken at four depths, 8 and 12 weeks after germination. Root weight was determined by weight loss after ashing the samples. Root weight decreased with depth, but increased with bulk density. Although root weight increased after 12 weeks, there was no significant difference between dates. When grown at the same bulk density, the root growth of all grasses was statistically the same at any given depth.